Protein replacement by digestible fibre in the diet of growing rabbits: 2-Impact on performances, digestive health and nitrogen output

The fattening performances, nitrogen excretion and health status of growing rabbits were studied in response to a linear reduction of the digestible fibre (DgF=water-insoluble pectins+hemicelluloses) to crude protein ratio (DFP) in four diets (from 1.01 to 1.55). As the crude protein level was reduced from 17.7% to 13.9% (in diets DFP1–DFP4), the DgF level was increased from 18.5% to 22.1%, without changes to poorly-digestible fibre levels (ADF=19%). A total of 644 rabbits per diet were used in a multi-site study (n=6). Between weaning (28d–37d according to sites) and 49d of age, reduction of the DFP ratio led to a linear decrease in weight gain (−4g/d between DFP1 and DFP4, P